package gitapp.oschina.net.my_osc.common;

import java.security.Key;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

/**
 * Created by houjianhua on 2016/10/25.
 */

public class CyptoUtils {
    public static final String ALGORITHM_DES = "DES/CBC/PKCS5Padding";

    public static String decode(String key, String data){
        if (data == null){
            return null;
        }
        try {
            DESKeySpec dks = new DESKeySpec(key.getBytes());
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            Key secretKey = keyFactory.generateSecret(dks);
            Cipher cipher = Cipher.getInstance(ALGORITHM_DES);
            IvParameterSpec iv = new IvParameterSpec("12345678".getBytes());
            AlgorithmParameterSpec parameterSpec = iv;
            cipher.init(Cipher.DECRYPT_MODE, secretKey, parameterSpec);
            return new String(cipher.doFinal(hex2byte(data.getBytes())));
        }catch (Exception e){
            e.printStackTrace();
            return data;
        }
    }

    private static byte[] hex2byte(byte[] b) {
        if((b.length%2)!=0)
            throw new IllegalArgumentException();
        byte[] b2 = new byte[b.length/2];
        for (int n = 0; n < b.length; n+=2) {
            String item = new String(b,n,2);
            b2[n/2] = (byte)Integer.parseInt(item,16);
        }
        return b2;
    }
}
